Syrian Deputy Oil Minister Abdo Hussameddin has announced his defection to the opposition, becoming the first high-ranking civilian official to abandon President Bashar al-Assad's regime since the Syrian uprising erupted a year ago.

Hussameddin announced in a four-minute video posted on YouTube that he was “joining the revolution of the people who reject injustice and the brutal campaign of the regime.”

He added he was aware that the regime could retaliate by burning down his home and persecuting his family.

Rami, the activist who shot the video of Hussameddin, told the AFP news agency in Beirut that the opposition helped arrange his resignation.

The Syrian government has not publicly commented on Hussameddin's announcement.

News of the Hussameddin defection came as UN humanitarian envoy Valerie Amos and a Syrian Red Crescent convoy were finally allowed into the devastated city of Homs for a brief visit as part of an effort to convince Damscus to grant aid teams access to the area.

Amos was quoted as saying that some areas of Homs had been "devastated" in a weeks-long offensive by Syrian government troops.

She also said that the bombed-out Baba Amr district felt like it had been closed down entirely.

Activists say hundreds of people have been killed in the intense shelling of the district, and that government troops committed massacres since they retook the area last week.

U.S. Prefers Diplomacy

In Washington, U.S. Secretary of State Hillary Clinton said the United States and its allies were stepping up efforts to aid the opposition, saying the Assad regime's human rights violations had reached "a new low."

U.S. Defense Secretary Leon Panetta testified before U.S. senators on March 7 that no options -- including military action -- had been ruled out to end the violence in Syria. But appearing before the Senate Armed Services Committee, Panetta said the limits of military force must be recognized.

However, Panetta told the Senate Armed Services Committee that the legal basis for any such action must be clear, and the limits of military force recognized.

He also said the Obama administration would prefer a diplomatic solution to the crisis.

Senior Senator and 2008 presidential nominee John McCain (Republican-Arizona) on March 5 suggested the United States should lead air strikes against Syria, saying that "it would be a moral and strategic defeat for the United States" if Assad were to remain in power.

"We have received information that in Libya, with the support of the authorities, there is a special training center for the so called Syrian revolutionaries and people are sent to Syria to attack the legal government," Churkin said. "This is completely unacceptable according to all standards of international law. Such activity is undermining the efforts of ensuring stability in the Middle East."

The United States and its allies are trying to overcome objections from Russia and China and win agreement on a new UN Security Council resolution that would exert pressure to end the Syrian violence.

Russia and China have vetoed two previous drafts, calling them unbalanced.

Beijing announced on March 8 that its envoy had talks in Syria this week with representatives of the government and the opposition.

China's Foreign Ministry said that during the talks, envoy Li Huaxin reiterated Beijing’s position that the Syrian crisis should be settled peacefully through dialogue.